Three-dimensional medical tissue implants are known. For example, U.S. Pat. No. 5,891,558 to Bell et al. discloses inter alia biopolymer foams as well as biocompatible constructs comprising such biopolymer foams, which can be used in medical implants to replace damaged or diseased tissue, or to provide scaffolds which, when occupied by e.g. host cells, are remodeled to become functional tissue. According to Bell et al. biopolymer foams can be reinforced by winding a biopolymer thread around a foam layer. Further, in U.S. Pat. No. 6,599,323 to Melican et al. it is suggested to reinforce a medical tissue implant, which comprises one or more layers of bioabsorbable polymeric foams, with a preferably bioabsorbable reinforcement component.
For some medical implantation applications—such as scaffolds used predominantly for soft tissue augmentation in breast reconstruction or revision surgery, nipple regeneration, various facial augmentations like chin augmentation, various hernia applications, rhinoplasty and scaffolds used for various tissue engineering purposes where the scaffold is used as a substrate for proliferation of cells ex-vivo or in-vivo or a combination of both—the implant to be introduced into a human or animal body should possess a certain amount of load-bearing capacity without being too rigid, something which otherwise may cause problems during implantation or increased local tissue reactions due to modulus mismatch, especially in soft tissue. Three-dimensional implants where the porosity is higher than 70%, and especially those which are based on or contain a foam-like structure, will—even if reinforced with other structures, components or materials—have a limited ability to withstand compressing forces unless the implant in question is made from stiff materials and thus becomes stiff and non-compliant for most or all soft tissue applications. In unorganized structures such as foams it may also be difficult to control the load-bearing capacity during manufacture of the structures in question. Unorganized porous structures suffer also from varying pore homogeneity, i.e. the porosity is not necessarily the same for all portions of the unorganized structure. Further, in unorganized porous structures, properties like porosity, bending stiffness and compression stiffness are usually strongly related to each other, i.e. in practice it may be difficult to produce a medical implant having a desired porosity and, at the same time, a desired bending or compression stiffness. It is furthermore difficult or impossible to combine different materials and consequently different material properties into a single porous scaffold, which further augment the difficulties and limitations when it comes to design scaffolds with optimal properties for various clinical needs and indications.